Apparatus for transmitting energy



May 7, 1935. 1. c. HARRIS ET AL APPARATUS FOR TRANSMITTING ENERGY FiledMarch 25, 1932 IN VE/V 70/? s Patented May 7, 1935 UNITED STATESAPPARATUS FOR TRANSMITTING ENERGY Irvin! C. Harris, Los Angeles, andBarry W.

Doubrava, Beverly Hills, Calif.

Application March 25,

is'claims.

This invention relates to methods of transmitting energy throughpassageways of small diameter from a source at one elevation to a lowerelevation for the purpose of actuating energy using devices at the lowerelevation, as for example, devices used in connection with the drillingand operation of wells, drainage of mines, and for other purposes.

Wells drilled for petroleum and gas are of relatively small diameter;and a great percentage of them are very deep. They penetrate bothunconsolidated and consolidated formations of great hardness andresistance to drilling operations; and the transmission of the necessaryenergy from the source above ground to the bottom for the operation ofthe cutting tools presents a difilcult problem, especially in thedrilling of the deeper wells.

The completed wells range in depth up to eight thousand feet and havestrings of easing ranging from 8%" down to 4%" in diameter. After thevirgin gas pressure has been depleted and the oil must be lifted byexternal means from depths of from one to several thousand feet, energymust be transmitted these distances through these small bores for thelifting of the oil to the ground surface.

Various methods have been used for transmitting the energy for thepurposes named with a measure of success, but attended by seriousdifficulties which leave much room for improvement. In drilling wells,two' methods of transmitting the energy to the bottom are in common use.With the churn-drill, or cable tool drill, the cutting bit is lifted anddropped repeatedly by means of a cable; and the energy is transmittedthrough the cable by the intermittent pulling of the cable by means atthe surface of the ground. With the rotary drill, the cutting bit isrotated about the axis of the bore under heavy rotative torque and underheavy downward pressure on thebit; and the energy is transmitted throughthe long, slender drill-stem from above ground to the bit as a torquewhich ranges up to a maximum that frequently twists the drill-stem intwo.

, The cable tool method has certain. advantages and certaindisadvantages which limit its use to certain fields. The rotary methodhas superseded the cable tool to a very large extent due to certainadvantages; but the method of transmitting the energy to the cuttingtools as a rotative torque, transmitted through a long slender drillstem, is one of the causes of the drilling of very crooked holes andmany other 1932, Serial No. 601,156

lift, and displacement gas-lift methods have been used quitesatisfactorily in certain ranges of operation; but they all have limitsas to the maximum depth from which they will pump oil satisfactorily;and there is need for pumping oil from depths beyond these limits.

Various methods have been considered for overcoming these difficulties,including electric, hydraulic, pneumatic, and mechanical means oftransmission of the energy. There are certain inherent obstacles thatprevent these from'being entirely satisfactory. Any method to becompletely satisfactory must fulfill the following requirements:

1st.-It must transmit the energy from above ground to the drilling,pumping, or other device in the well without torque or twisting actionon the pipe or other member connecting the device at the bottom with theapparatus above ground.

2nd.-It must transmit the energy from above ground to the device at thebottom without subjecting the pipe or other connecting means toreversals or large variations in stress, either in the form of rotativetorque, axial tension or compression, or hydraulic pressure within orwithout the pipe.

3rd.It must transmit the energy from above ground to the device at thebottom without subjecting a long column, or long columns of fluid, torepeated, sudden, or severe changes in flow or pressure.

The present invention provides a method of transmitting energy which,for example, may be used for transmitting energy from above ground tothe bottom of a well or shaft of any depth for the operation of anyenergy using device at the bottom; and it accomplishes the result bymeans which meet all of the requirements stated above. We attain thestated objective by the means described in the following specificationand illustrated by the accompanying drawing of a specific embodiment ofthe invention, in which, Fig. 1 is an axial section of the apparatusinstalled in a well and adapted to pumping liquid from the well, Fig. 2a view showing details of motor valve.

' The apparatus installed in the well consists of two concentric stringsof tubing, parts I9 and I4 of Fig. 1, connecting the various units witheachother and with the apparatus above ground, and providing a conduitfor the circulation of a flow o! fluid downward to the. bottom of theapparatus from above ground in the inside of the inner string of tubingI4, as indicated by the arrows, and upward to the starting point in thespace between the two strings of tubing, as indicated by the arrows.Throughout parts of the length of the apparatus, other strings of tubingof small bore, designated gas-lines, parts I2 and 2I, are installedwithin the inner tubing I4, making three concentric strings for part ofthe length and two for the rest.

At the lower end of the apparatus, is an assembly of parts constitutinga separator and a pump, of which parts I are pump inlet valves, parts 2pump discharge valves, part 3 the pump cylinder, part 4 the powercylinder, 5, 6, 8, 9, 40, and 4| passageways, part 'I a valvecontrolling the power cylinder, ID the nozzle sleeve, II the separatorchamber, and 8 the outlet from the separator chamber.

Situated at a point above the separator is a mixer chamber I5 supportedby a spider It, the mixer chamber being a cylinder, open at the bottom,closed at the top, and connected to the separator at the bottom by meansof gas-line I2 in such a way that gas ascending in I2 will enter mixerchamber I5 near the top, The descending flow of fluid can pass the mixerchamber, and gas entering the chamber may pass out at the bottom andjoin the descending flow of fluid.

At a point above the mixer is a second separator, which may be the sameas the lower one or of an inverted form, as shown, of which, 20 is theseparator chamber, formed by inner sleeve I8 and outer sleeve I9. Theascending flow of fluid passes through nozzles II. The descending flowof fluid passes the separator through openings in the supporting spider.

At a point near the upper end of the apparatus in the well is a secondmixer of the same construction as the lower one but differentlyconnected as to the gas-line. The mixer chamber is indicated at 23; andthe descending flow of fluid passes it through passageways 22. Thegas-line 2| leads from the second, or upper, separator through the uppermixer without connecting to it and conveys gas to outlet 24. Gas maybeconveyed into the upper mixer through the inlet 25 and the connectingpassageways, as indicated by arrows.

Above ground is a tank 21, and some form of a pump, indicated at 26, isconnected with the apparatus in the well and tank 21 by. passageways 29and 30 in a manner such that the pump 26 may be used to pump fluid fromthe tank2'l through the circuit of conduits in the well, as described,and back to the tank again.

The method of operation is described as follows: With an initial chargeof the liquid to be pumped in tank 21 suflicient to fill the system, thepump 26 is operated to establish and continuously maintain a circulationof the liquid to the separator chamber II through the inner tubing I4and back to the point of beginning through the space between theinner'tubing I4 and the outer tubing I3, and through the passagewaysthrough the two separators and th two mlxers as indicated by the arrowson the drawing and hereinbefore described. An initial charge of gas fromthe well, an adjacent well, or from any other source, admitted throughinlet 36, is compressed by compressor 85 and introduced through inlet 25to the circulation in the well, into mixer chamber 23 'where' it passesdownward into the flow of liquid moving downward in the inner tubing.The velocity of flow of the liquid is maintained far above the rate ofrise of gas in the liquid clue to its buoyancy; and the gas is carrieddownward with the liquid to the separator chamber II at the bottom; andthe gas is compressed by the liquid in descending from the pressure atmixer chamber 23 to the pressure at the separator chamber II, the amountof compression being proportional to the weight of the column of liquidand gas between the two points.

The mixture of liquid and gas enters the separator chamber II throughnozzles I0, which are spiral passages, as indicated in Fig. 2, whichcause the mixture to whirl and form a vortex withinthe chamber. Theliquid weighs from 50' to 62 pounds per cubic foot and the gas weighsfrom .08 pounds to 10 pounds per cubic foot, approximately, -the lowervalue being at about atmospheric pressure and the higher at about 2000pounds per square inch. Owing to this large difference in weight of theliquid and the gas and the fact that the mixture is forced by thepressure of the circulating pump 26 and the shape, dimensions, andangularity of the nozzles I0, to enter chamber II and move in a spiralof small diameter and at high velocity,-thereby causing a largecentrifugal effect,-the liquid, due to its greater weight, is forced tomove spirally downward in a thin sheet against the outer cylindri- -ca1wall of separator chamber I I, and the gas,

due to its lighter weight, is forced to form a core of gas, in thecenter of chamber II, inside of the liquid.

Gas may be withdrawn at the upper end of chamber I I, near the center,through passageway 9, provided the rate of withdrawal is not greaterthan that of the gas entering through nozzles I0. Gas in excess of theamount passing out through passageway 9, passes out through outlet 8with the liquid. Withdrawal of gas through outlet 9 requires a slightdrop in pressure beyond outlet 9 to cause flow from separator chamber IIto the cylinder 4, through valve 1.. The drop in pressure and the amountof gas withdrawn is regulated by the conditions in the motor to anamount less than the total amount of gas circulated and entering chamberI I through nozzles I0. As long as there is an excess of gas beyond thewithdrawal through outlet 9, the excess gas must pass out with theliquid through outlet 8. Liquid can not pass out through outlet 9 aslong as there is suflicient gas to keep the upper end of the chamber II,above the level of the nozzles I0, filled with gas.

The gas which passes out through outlet 8 with the liquid, passes upwardto the second separator chamber 20 where the same action takes place asdescribed for separator chamber II, except that the second separator isan inverted form which functions in a similar manner. The liquid passesupward in the conduit between the inner tubing and the outer tubing,--

tubing I3 and I 4,--to the tank 21; and the gas passes upward throughgas-line 2| to outlet 24. Outlet 24 may be connectedto outlet 25 directand'the gas re-circulated; but, generally, the gas is taken from outlet24 to a treatment plant. The treatment plant for treating the gas,indicated by parts 33, ll, 35, and 36 on the drawing,

may be of any type or may consist of any equivalent that will insure thedelivery through inlet 2! of the quality,fquantity, and pressure of gasrequired for the operation of the apparatus.

' The circulations of liquid and gas and mixture of liquid and gas areforced to take the various paths, as indicated by thev arrows on thedrawing and as described herein, for the reason that the pressuregradients throughout the circuits are such as to produce thesecirculations. The forces producing the separations have been described.The separator H and the mixer I! are at widely different elevationswhich may be of the order of many hundreds of feet, even thousands-offeet. The weight of the gas per square inch of cross section, inthegas-line .l2 between the separator II and the mixer I5,

is a very small fraction of the weight of the fluid, per square inch ofcross section, in the space between tubing l4 and tubing l2, between thetwo elevations. The friction loss in the gasline I! is, also, less thanthe friction loss in the space between tubing I4 and tubing l2, owing tothe difference in the friction losses of liquids and gases. Due to thesedifferences, there is a difference of pressure between the outlet 9 ofthe separator and the gas inlet of the mixer l5, as long as gas alone isallowed to pass through gas-line l2; and the pressure difference mayrange up to 1000 pounds per square inch in deep installations. Thisdifference in pressure and the quantity of gas 'withdrawn from theseparator through outlet 9 and returned to the circulation through themixer l5, are measures of the energy used in the energy using device,the pumping apparatus represented by the motor cylinder 4 in thisembodiment of the invention. This energy, withdrawn from the circulationcircuit at this point and consumed, is put into the circulation circuitby the pumping means at the upper end of the apparatus and istransmitted through the circulation circuit as described.

It has been stated how the outflow of gas from separator ll throughoutlet 9 is controlled. The return of the gas entering the mixer throughgas-line l2 to the descending fiow of mixture is forced by definite andpositive causes. The gas must pass out of the mixer as fast as it comesin; because any tendency to reduce the flow of gas out of the mixer ismet by a rise in pressure, due to the decrease in pressure drop inconduit l2,-caused by the decreased flow,- which rise in pressureovercomes the tendency to reduce the flow. The pressure in the mixerchamber must be the same as the pressure at that elevation in theconduit carrying the descending flow of fiuid with which itcommunicates, and cannot rise above that pressure. Liquid cannot enterthe mixer chamber and pass out into gas-line l2 as long as the upwardflow of gas in gas-line l2 and into the mixer is maintained. The actionthat takes place between thev second separator 20 and the second.

mixer 23 is very much the same, except that the difference in pressurebetween the two is only just enough for the regulation of the flow.

No liquid can go out through the gas outlets of the separators as longas there is more gas coming into the separators with the mixture than isgoing through the gas outlets; and the excess gas goes out of theseparators with the liquid. It is merely necessary to maintain in thecirculating system gas in excess of that required to pass through theenergy using device and gas-line l2, and to regulate the flow of gasbetween outlet 24 and inlet 25.

The gas separated out by separator chamber H is conveyed throughpassageway 9 to valve I, which controls its admission to and dischargefrom motor cylinder 4. Valve 1 may be of any type and actuated in anymanner, such as by means of a valve-rod 3|, which is actuated byengagement with shoulders 32 and 39 of the piston in motor cylinder 4,as the piston approaches the respective ends of the pistons stroke. Themotor piston is reciprocated by the alternate admission and discharge ofgas through the passages ll and II, which are opened and closed insequence by valve 1, after the manner of an ordinary double acting steampump. The gas enters the motor cylinder from separator ll, through port9, valve I, and passage (or II) at the pressure of the separator chamberll, less a slight friction drop; and. upon completion of the halfstroke, is vented through passage 0 (or 4|) valve 1, and gasline II, tomixer l5, and expands to the lower pressure of mixer l5,less a smallfriction drop. The returnhalf of the stroke is made with the oppositeside of the piston being acted upon by the higher pressure from theseparator II and the first stated side by the lower pressure of themixer I 5, plus a slight difference due to the weight of the column ofgas under pressure between the two points.

The desired pressure difference across the piston in motor cylinder 4 iscontrolled by the distance between the mixer l5 and the separator H andthe amount and relative quantities of liquid and gas circulated betweenthe two points. The descending column of mixture and the ascendingcolumn of gas must be in dynamic pressure balance between the twoelevations, allowing for all factors. In the descending column, there isthe unit weight of the liquid, the unit weight of the gas,allowing forthe progressive increase in weight with pressure,and the friction loss.In the ascending column, there is the unit weight of the gas-allowingfor the progressive change in weight with pressure,the friction loss,and the pressure difference utilized by the motor. The aggregate ofthese factors in the ascending column must balance the descendingcolumn. This balance is produced and maintained by proper proportioningof the component parts in installation and by manual or automaticregulation of the circulating pump, compressor, and other apparatus atthe upper end of the apparatus, the means of accomplishing thisregulation not being parts of thepresent invention.

In the specific embodiment of the invention shown, the gas used throughthe motor is returned to the descending column of the circulatingcircuit. It is not necessary to return it at this point. It may bereturned at other points in the circulation having a similarrelationship as to pressure as compared with the pressure at the lowerseparator; For example. the gas may be returned from the motor to theascending column at a point having a suitable pressure; or, it may bereturned at the upper mixer, dispensing with the lower mixer. In thesecases, the gas has farther to travel in making the circuit, thedistribution of the gas is different in the descending column, and theperformance is modified; but the same laws govseparator may be varied.It may be placed at the upper end 01' the apparatus; in which case, thegas separated out by it goes to the treatment plant at a lower pressurethan is the case when located as previously described; and thisdifference in pressure is made up by the compressor 3 before the gas isreturned to the circulation at mixer 23. Tank 21 may be open as shown,or closed; and the tank ii and the separator 23 may be operated atatmospheric pressure or with a back-pressure above atmospheric, allwithout departure from the basic principles oi this invention.

Gas in excess or that needed by the local circuit through pump powercylinder 6 is automatically rejected at it by separator passes upward toseparator 25, where it is separated irom the liquid and conveyed throughpassageway 26 to outlet 26. Separator 2i! is located at a distance belowground such that the pressure of the gas separated out and conveyed tooutlet 2 3 is slightly higher than the pressure produced by circulatingpump 23 at the point where gas from mixer it enters the descending flowof liquid at 22. This makes it'possible for the gas issuing at outlet itto be put back into the circulation through inlet 22% and mixer 23without rte-compressing; thus saving the use of a mechanical compressorat the ground surface.

when pumping petroleum, a certain amount oi gas comes into the circuitwith the oil and insures an abundance of gas, if there are no largelosses, after the initial charge is introduced. it is found that gas,thus circulated, accumulates gasoline vapor and that it can be putthrough apparatus for extracting the gasoline indicated at 3?); afterwhich, the gas is returned to the circulation again. This operation canbe readily provided iorbetween outlet 2% and inlet Having described themanner ofreciprocating the power piston oi the pump at the bottom, it

is easy to be seen that the pump cylinder .3 will draw oil from thespace in the well external to the apparatus through inlet valves ianddischarge it through discharge valves 2 and passageway 6 into thecirculating system at Q, from which point, the pumped oil is carriedupward with the circulating oil to tank 2?; and the excess of oilresulting is withdrawn at outlet 28.

It is to be seen that the same system of transmitting energy can be usedto operate any other kind of apparatus at the bottom of a well, and thatit may be used in places other than in a well. In the specificembodiment used to illustrate the invention, the-fluid pumped by theenergy using device is injected into the circulartion circuit for theprimary purpose of conveying it to the ground level without thenecessity of providing a separate conduit; but this is not an essentialpart of the present invention.

Having described the invention it is pointed out that it fulfills all ofthe stated objects, in that it provides means of transmitting energyfrom above ground level to any depth in a well without submitting anypart of the connecting structure to rotative torque, without subjectingthe connecting pipes or strings of tubing to reversals or largevariations in stress either in the form of rotative torque. axialtension or compression, or hydraulic pressure, and without subjecting acolumn, or columns, of fluid to repressure. The circulation ismaintained as a tion in any case; but, when the liquid is being injectedinto the circulation, a somewhat larger volume of gas is being withdrawnfrom an adjacent point in the circulation at the same halfstroke; andthe same amount of gas, expanded to larger volume, withdrawn at thepreceding half-stroke, is returned to the circulation at a lowerpressure and hundreds of feet higher up the ascending column of fluid atthe said same half-stroke. The net effect on the circulation is verysmall and not disturbing in the least. The pump is reciprocated by gas,an expansibie fluid which gives a cushioning effect; and there are nosevere shocks such as accompany the use of liquid alone iorsuchpurpose's.

Attention is called to the fact that the use of a mixture of liquid andgas in circulation, as described, performs important functions. Itprovides an hydro-pneumatic compressor which automatically supplies thevariable gas pressures required in operating the apparatus with theenergy using device at distances below the up crating life of a singleinstallation, requiring 'gas pressures that may range from 300 to 3009pounds per square inch. To accomplish this result with mechanicalcompressors would require a very costly installation of severalcompressors; whereas, with the apparatus described, the high pressureand the variable pressure requirements are met by a very simple andcomparatively inexpensive liquid pump, pump 26, with a maximum pressurecapacity of not over 800 pounds per square inch. Thehydro-pneumaticcompressor is very eillcient, is practically isothermalin operation, and involves no cooling problems. With a mechanicalcompressor in stallation, cooling of the compressor and the gas would berequired. The variations in the depth at which the energy using deviceoperates and the consequent gas pressures required are met by changes inthe elevations of the said device and the separators and mixers. in thepressures required to be delivered by pump 26 are small compared withthe changes in the pressure at the said device.

Attention is called to the fact that the method is very flexible andcapable of a large variation in method of operation to suit the specificpurposes to be accomplished or the characteristics of the availablefacilities to be use in combination with the method. The pumping meansat the ground surface may be operated to maintain a constant rate offlow of liquid, the pressure varying as necessary, or at a constantpressure with the flow varying as necessary. Each method has its ownperformance characteristics which suit certain conditions to beencountered in certain fields.

The changes We have illustrated and described a preferred principles ofthe invention. Various combinations of parts are possible; It may beoperated with all of the component, parts described in use, or with someof them omitted or modified.

pcated. sudden, or severe changes in flow or It may be operated'with asecond mixer and a second separator, or with either or both omitted orlocated in a different position in the circuit. Diflerent combinationsthe conduits for the circulation of the liquid and the conveyance of thegas are possible. we do not limit ourselves to the exact details ofconstruction disclosed but may employ such changes in construction andarrangement of parts, and such modifications and equivalents as comewithin the scope of the appended claims.

We claim:

1. In apparatus of the character described,

' pumping means at the upper end of the apparathe mixer; and means ofintroducing gas into the circulation of fluid.

2. In apparatus of the character described, pumping means at the upperend of the apparatus, strings of tubing, connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation of fluid may be maintained by the pumpingmeans; a separator, near the lower end of the' strings of tubing,comprising a chamber, an outlet for fluid connected to the conduitconveying the flow of fluid ascending toward the pumping means, anoutlet for gas near the axis of the chamber, and inlet passagesconnected to the conduit conveying the flow or fluid descending from thepumping means, the inlet passages being so formed and .disposed as tocause the entering fluid to enter and proceed in a generally spiraldirection along the outer wall of the chamber; an energy using deviceadapted to receive gas from the separator; a mixer adapted to receivegas from the said device and return in to the circulation of fluid;means oi conveying gas from the said device to the mixer; and means ofintroducing gas into the circulation of fluid.

3. In apparatus of the character described,

" pumping means at the upper end of the apparatus, strings of tubing,connected to the pumping means and connected together at their lowerends in a manner to form a circuit through which a circulation of fluidmay be maintained by the pumping means; a separator, near the lower endof the strings of tubing, comprising a chamber, an outlet for fluidconnected to the conduit conveying thegflow of fluid ascending towardthe pumping means, an outlet ior gas near the upper end of the chamber,and inlet passages connected to the conduit conveying the flow of fluiddescending from the pumping means, the inlet passages being soiormed anddisposed as to cause the entering fluid to enter the separator; a mixeradapted to receive gas from thesaid device and return it to the circulation of fluid; means of conveyin as from the said device to the mixer;and means ofintroducing gas into-the circulation of fluid.

4. In apparatus of the character. described,

pumping means at the upper end of the apparatus, strings of tubing,connected to the pumping means and connected together at their lowerends in a manner to form a circuit through which a circulation of fluidmay be maintained by the pumping means; a separator, near the lower endof the strings of tubing, comprising a chamber, an outlet for fluid,connected to the conduit conveying the flow of fluid ascending towardthe pumping means, and outlet for gas near the upper end of the chamber,and inlet passages connected to the conduit conveying the flow of fluiddescending from the pumping means, the inlet passages being so formedand disposed as to cause the entering fluid to enter and proceed in agenerally spiral direction along the outer wall of the chamber, thedirection of rotation of the spirally moving fluid being clockwise whenviewed from above; an energy using device adapted to receive gas fromthe separa- V tor; a mixer adapted to receive gas from the said deviceand return it to the circulation of fluid; means of conveying gas fromthe saiddevice to the mixer; and means of introducing gas into thecirculation of fluid.

5. In apparatus of the character described, pumping meansat the upperend of the apparatus, strings of tubing, connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation of fluid may be maintained by the pumpingmeans; a separator, near the lower end of the strings of tubing, adaptedto separate gas from liquid; a mixer situated at a distance above theseparator and comprising a chamber with a gas inlet and a connectionwith a conduit oi the circuit which conveys the flow of fluid circulatedby the pumping means; an energy using device connected to receive gasfrom the separator and discharge the same into the inlet of the mixer;and means of introducing gas into the circulation of fluid.

6. In apparatus of the character described, pumping means at the upperend of the apparatus, two strings of tubing, connected to the pumpingmeans and connected together at their lower ends in a manner to form acircuit through which a circulation of fluid may be maintained by thepumping means, the connecting means comprising a separator, consistingoia chamber, an outlet for fluid connected to the conduit conveying theflow of fluid ascending toward the pumping means, a gas outlet near theupper end of the axis or the chamber, and inlet' passages connected tothe conduit conveying the flow oi fluid descending from the pumpingmeans, the inlet passages being so constructed and disposed as to causethe entering fluid to whirl spirally along the outer wall of thechamber; a mixer situated at a distance above the separator andcomprising a chamber having a gas inlet and a connection with a conduitconveying the flow oifluid circulated by the pumping means; an energy,using' device adapted to receive gas from the gasoutlet of theseparator; a conduit connecting the energy using device with the gasinlet of the mixer and adapted toconvey to themixer gas'exh austed bythe said device; and means oi introducing gas into the circulation oifluid.

'7. In apparatus of the character described. pumping means at the upperend or the apparatus, an assembly of tubing, connected to the pumpingmeans and connected together at the lower end in a manner to provide acircuit of conduit through which a circulation of fluid may bemaintained by the pumping means; an energy using device attached at thelower end of the assembly of tubing; a separator adjacent to the saiddevice and connected to it and to the circuit of conduit and adapted toseparate gas from the circulating fluid and deliver it to the saiddevice; a mixer situated at a distance above the separator and connectedand adapted to receive gas from the said device and deliver it into theconduit conveying the flow of fluid descending from the pumping means; asecond separator situated above the mixer'aforesaid and connected intothe conduit conveying the flow of fluid ascending toward the pumpingmeans;

a second mixer situated at a distance above the second separator andconnected into the conduit conveying the flow oi fluid descending fromthe pumping means; means of introducing gas into the circulation offluid; and a conduit connecting the gas outlet of the second separatorwith the gas inlet of the second mixer.

8. In apparatus of the character described, pumping means at the upperend of the apparatus, an assembly of tubing, connected to the pumpingmeans and connected together at the lower end in a manner to provide acircuit of conduit through which a circulation of fluid may bemaintained by the pumping means; an energy using device attached at thelower end of the assembly of tubing; a separator adjacent to the saiddevice and connected to it and to the circuit of conduit and adapted toseparate gas from the circulating fluid and deliver it to the saiddevice; a mixer situated at a distance above the separator andconnectedand adapted to receive gas from the said device and deliver it into theconduit conveying the flow oi fluid descending from the pumping means; asecond separator situated above the 'mixer aforesaid and a second mixersituated at a distance above the second separator, the second separatorbeing adapted to separate gas from the fluid ascending from the, lowerseparator to the pumping means, and the second mixer being adapted todeliver gas into the flow oi fluid descending from the pumping means; aline of conduit connected second separator to the ground surface, thenceto a plant for treating the gas, thence to the gas inlet or the secondmixer.

9. In apparatus or the character described, pumping means near theground level; strings of tubing, installed in a well, connected to thepumping means and connected together at their lowerends in a manner toform a circuit through which a circulation of fluid may be maintained bythe pumping means; a separator, near the lower end oi-the' strings oftubing, adapted to separate gas from liquid; an energy using deviceadapted to receive gas from the separator; a mixer to receive gas fromthe said device and return it to the circulation of fluid; a, secondseparator situated above the mixer and adapted to separate gas from theflow oi fluidascending from the flrst named separator; a line oi conduitconnected to convey gas from the gas outlet of the second separator to aplant for treating the gas; means or introducing gas intothecirculationor fluid.

10. In apparatusoi the character described,

to convey gas from the gas outlet oi the pumping means near the groundlevel; strings of tubing, installed in a well, connected to the pumpingmeans and connected together at their lower ends in a manner to form acircuit throughwhich a circulation of fluid may be above the separatorand adapted to receive gas from the said device and return it to theflow of fluid descending from the pumping means; an upper mixer situatednear the upper end of the apparatus and comprising a chamber with abottom outlet connected to the conduit conveying the flow of fluiddescending from pumping means and a gas inlet at the upperend-connected-to a source from which compressedgas may be supplied.

11. In apparatus of the character described, pumping means at the upperend oi the apparatus; strings of tubing connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation of fluid may be maintained by the pumpingmeans; a separator, near the lower end of the strings of tubing, adaptedto separate gas from liquid; an energy using device adapted to receivegas from the separator; a mixer adapted to receive gas from the saiddevice and return it to the circulation of fluid; means of conveying gasfrom the said device to the'mixer; means of introducing into andmaintaining in the circulation the required amount of liquid; means ofintroducing into and maintaining in the circulation the required amountor gas.

12. In apparatus of the character described, pumping means at the upperend of the apparatus; strings of tubing connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which acirculation of fluid may be maintained by the pumpingmeans; a separator, near the lower ends of the strings of tubing,comprising a chamber, an outlet for fluid connected'to the conduitconveying the flow or fluid toward the pumping means, an outlet for gasnear the upper end of the chamber, and inlet es connected to the conduitconveying the flow oi fluid descending from the pumping means; an energyusing device adapted to receive gas from the gas outlet of theseparator; a mixer connected andadapted to recei've gas from thesaiddevice and return the gas to the circulation of fluid at a point havinga pressure lower than the pressure at the gas outlet of the separator;means of maintaining liquid and gas within the circulation system in therequired quantity.

13. In apparatus of the character described, pumping means at the upperend of the apparatus; strings of tubing connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation oi. fluid may be maintained by the pumpingmeans; a separator, near the lower end or the strings of tubing, adaptedto separate gas from liquid; an energy using device'adapted to receivegas from the separator; a mixer connected-and adapted to receive gasfrom the said device and return it to a, point in the conduit carryingthe flow or fluid ascending from the separator, the said point having apressure lower than the pressure of the gas delivered from the separatorto the said device; means of maintaining liquid and gas within thecirculation system in the required amount. I v,

14. In apparatus of the character described, pumping means at the upperend of the apparatus; strings of tubing connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation of fluid may be maintained by the pumpingmeans; a separator, near the lower end of the strings of tubing, adaptedto separate gas from liquid; an energy using device adapted to receivegas-from the separator; a mixer connected and adapted to receive gasfrom the said device and return it to a point in the conduit carryingthe flow of fluid descending to the separator, the said point having apres-- sure lower than the pressure of the gas de- 7 connected andadapted to receive gas from the livered from the separator to the saiddevice; means of maintaining liquid and gas within the circulationsystem in the required amount.

15. In apparatus of the character described, pumping means at the upperend of the apparatus; strings of tubing connected to the pumping meansand connected together at their lower ends in a manner to form a circuitthrough which a circulation of fluid may be maintained by the pumpingmeans; a separator, near the lower end of the strings of tubing, adaptedto separate gas from liquid; an energy using device adapted to receivegas from the separator; a mixer connected and adapted to receive gasfrom the said device and return it to a point in the circulation offluid having a pressure lower than the pressure of the gas received bythe said device from the separator; a second separator near theupper-end oi the apparatus and connected and adapted to separate gasfrom the fluid in the circulation ascending to it from below; a secondmixer near the upper end of the apparatus and adapted to inject gas intothe circulation circuit; means of conveying gas by the pumping means; aseparator, near the lower end of the apparatus, adapted to separate gasfrom the fluid in the circulation; an energyusing device adapted to usegas from the separator to actuate the said device; a mixer said deviceand return it to the circulation at a point having a pressure lower thanthe pressure of the gas received by the device from the separator; asecond separator near the upper end of the apparatus and connectedandadapted to separate gas from the fluid inthe circulation ascending to itfrom below; a second mixer near the upper end of the apparatus andadapted to inject gas into the circulation circuit; means of conveyinggas from the second separator to a plant for treating the gas andreturning it to and injecting it into the mixer; means of'supplyingliquid and gas to the circulation system.

H. W. DOUBRAVA;

IRVING C. HARRIS.

